This elite will be given "credits" - the vouchers - which they will be able to exchange for extra courses, which could be a Saturday class in Mandarin, a summer school at a university or even a maths and science programme run by American space agency Nasa.

Ministers want schools to give special consideration to bright children from poor families whose "potential" has not been fulfilled, in a bid to stop middle-class parents monopolising the scheme.

The Government already requires secondary schools to identify children in the top five per cent of their intake, as measured by results achieved in national English and maths tests at the end of primary education, and put them forward for programmes run by the National Academy of Gifted and Talented Youth based at Warwick University.

But Lord Adonis, the architect of this scheme, has moved to double its size after becoming frustrated with the slow progress many comprehensives have made in identifying bright pupils.

He said: "The national register set up earlier this year will enable thousands more gifted and talented children to be identified, especially late developers and those underachieving because of social disadvantage.

"This register will ensure they are identified early and get the appropriate learning opportunities."

Teachers who are ideologically opposed to spotlighting the brightest have succeeded in stifling the scheme to such an extent that about 30 per cent of secondary schools have failed to put forward any pupils.

The Government's scheme will be administered by the not-for-profit Centre for British Teachers. Start-up funding of £65 million will pay for the courses.

Children will initially get 151 credits. A place at a university summer school might cost 100 credits, an evening online course 50 or a Saturday morning class 80.

Tim Emmett, the teacher centre's development director, said middle class pupils would not be excluded.

But he added: "The Government is seeing this as part of school improvement rather than a lifeboat for a few bright children.

"If you can raise the meter for 10 per cent of children in a school you can do it for the other 90 per cent as well."